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  2. Horizon - Wikipedia

    en.wikipedia.org/wiki/Horizon

    For example, for an observer B with a height of h B =1.70 m standing on the ground, the horizon is D B =4.65 km away. For a tower with a height of h L =100 m, the horizon distance is D L =35.7 km. Thus an observer on a beach can see the top of the tower as long as it is not more than D BL =40.35 km away.

  3. Comoving and proper distances - Wikipedia

    en.wikipedia.org/wiki/Comoving_and_proper_distances

    The comoving distance from an observer to a distant object (e.g. galaxy) can be computed by the following formula (derived using the Friedmann–Lemaître–Robertson–Walker metric): = ′ (′) where a(t′) is the scale factor, t e is the time of emission of the photons detected by the observer, t is the present time, and c is the speed of ...

  4. Visibility - Wikipedia

    en.wikipedia.org/wiki/Visibility

    The height of the elevated point plus the Earth radius form its hypotenuse. If both the eyes and the object are raised above the reference plane, there are two right-angled triangles. If both the eyes and the object are raised above the reference plane, there are two right-angled triangles.

  5. Equations for a falling body - Wikipedia

    en.wikipedia.org/wiki/Equations_for_a_falling_body

    [1] [2] He measured elapsed time with a water clock, using an "extremely accurate balance" to measure the amount of water. [note 1] The equations ignore air resistance, which has a dramatic effect on objects falling an appreciable distance in air, causing them to quickly approach a terminal velocity. The effect of air resistance varies ...

  6. Stadiametric rangefinding - Wikipedia

    en.wikipedia.org/wiki/Stadiametric_rangefinding

    Range (r) = approximate height of object (h) × (1000 ÷ aperture in milliradians (a)) r = h(1000/a) → where r and h are identical units, and a is in milliradians. r = h/a → where r and h are identical units, and a is in radians. The above formula functions for any system of linear measure provided r and h are calculated with the same units.

  7. Intercept method - Wikipedia

    en.wikipedia.org/wiki/Intercept_method

    On the chart he marks the assumed position AP and draws a line in the direction of the azimuth Zn. He then measures the intercept distance along this azimuth line, towards the body if Ho>Hc and away from it if Ho<Hc. At this new point he draws a perpendicular to the azimuth line and that is the line of position LOP at the moment of the observation.

  8. Vincenty's formulae - Wikipedia

    en.wikipedia.org/wiki/Vincenty's_formulae

    Vincenty's formulae are two related iterative methods used in geodesy to calculate the distance between two points on the surface of a spheroid, developed by Thaddeus Vincenty (1975a). They are based on the assumption that the figure of the Earth is an oblate spheroid, and hence are more accurate than methods that assume a spherical Earth, such ...

  9. Range of a projectile - Wikipedia

    en.wikipedia.org/wiki/Range_of_a_projectile

    We are interested in the time when the projectile returns to the same height it originated. Let t g be any time when the height of the projectile is equal to its initial value. 0 = v t sin ⁡ θ − 1 2 g t 2 {\displaystyle 0=vt\sin \theta -{\frac {1}{2}}gt^{2}}